Fill in the blanks.
The ratio of the number of boys to the number of girls in Class A is 7 : 3.
The ratio of the number of boys to the number of girls in Class B is 3 : 8.
The number of boys is the same.
- Number of boys in Class A = _____ u
- Number of girls in Class B = _____ u
- Number of children in Class B = _____ u
- Total number of children = _____ u
Class A |
Class B |
Boys |
Girls |
Boys |
Girls |
7 x 3 |
3 x 3 |
3 x 7 |
8 x 7 |
21 u |
9 u |
21 u |
56 u |
(a)
Change ratio into units.
The number of boys in Class A and Class B is the same.
LCM of 7 and 3 = 21
Class A
Boys : Girls
7 : 3
(x3) 21 : 9
Class B
Boys : Girls
3 : 8
(x7) 21 : 56
Number of boys in Class A = 21 u
(b)
Number of girls in Class B = 56 u
(c)
Number of children in Class B
= 21 u + 56 u
= 77 u
(d)
Number of children in Class A
= 21 u + 9 u
= 30 u
Total number of children
= 77 u + 30 u
= 107 u
Answer(s): (a) 21; (b) 56; (c) 77; (d) 107